Manhole cover and mounting means therefor



Feb. 27, 1968 E p WORTHEN ET AL 3,370,741

MANHOLE COVER AND MOUNTING MEANS THEREFOH 2 Sheets-Sheet l OriginalFiled Aug. 22, 1960 Feb. 27, 1968 E. P. WORTHEN ET Ax. 3,370,741

MANHOLE COVER AND MOUNTING MEANS THEREFOR Original Filed Aug. 22. 1960 2Sheets-Sheet Wm, NYM,

ELL #nur ATTORNEY United States Patent Otlce 3,370,741 Patented Feb. 27,1968 3,370,741 MANHOLE COVER AND MOUNTING MEANS THEREFOR Eugene PorterWorthen, Braintree, and John Henry Stelling, South Yarmouth, Mass.,assignors to Bethlehem Steel Corporation, a corporation of DelawareOriginal application Aug. 22, 1960, Ser. No. 51,043, now Patent No.3,254,705. Divided and this application Mar. 8, 1965, Ser. No. 437,749

2 Claims. (Cl. 220-25) ABSTRACT OF THE DISCLOSURE A manhole cover ismounted, inside a shell, through two pivotable links to a pin above themanhole opening, to permit the manhole cover to be swung to either sideof the manhole opening. The links are above the manhole opening, thuspermitting free access to the shell interior when the manhole cover isswung aside.

This application is a division of copending application Ser. No. 51,043,tiled Aug. 22, 1960, now Patent No. 3,254,705, for TubesheetlessButtwelded U-Tube Type Combined Steam Generator and Non-Condensable GasExtractor.

The present invention relates broadly to a manhole cover and means formounting the same to the shell of a heat exchanger. More specifically,the present invention relates to a manhole cover and means for mountingthe same to the inside of a steam generator so as to permit the same tobe swung to either side of a manhole in the shell of the steamgenerator.

The present invention as described herein in connection with atubesheetless, U-tube type steam generator employing a primary heatingmedium to boil a secondary uid, such as Water, to convert the same intosteam and, in particular, with such a steam generator associated with anuclear power plant, the primary heating medium being saturated stea-mfrom a nuclear reactor of the boiling water type. In a representativesystem, steam from such a reactor is introduced into the steam generatorto raise steam in the secondary system. The secondary steam may then beused to operate a power plant. Of course, the steam generator describedherein in connection with the present invention may use, as the primaryheating medium, hot water or other hot iluid and may also usesuperheated steam.

As an example of the working conditions under which a steam generator ofthe type above described may operate, the said steam generator mayreceive primary saturated steam from a reactor at a pressure of 1000p.s.i.a. (approximately 545 F.) to generate secondary saturated steam ata pressure of 600 p.s.i.a. (approximately 486 F.), the primary steamcondensate leaving at about 545 F. and the secondary feed entering atabout 486 F. These iigures are given by way of illustration only.

Tremendous diiculties and high costs have been involved in the designand construction of conventional U-tube type steam generators used inconjunction with nuclear power plants. In addition to the hightemperatures and pressures encountered, there is also the necessity ofinsuring that the primary steam, which may be contaminated byradioactive material, will not endanger personnel in the event ofleakage in the equipment.

A steam generator of the type above described will ordinarily have anumber of tubes therein which, from time to time, may require servicingof one sort or another. This in turn means that access through the shellof the steam generator to the interior thereof may be necessary fromtime to time, for instance to plug tubes or to withdraw tubes from theinterior of the steam generator and to replace them.

An object of this invention is to provide a large manhole door or covereasily opened to either side of the manhole in the steam generator,giving quick and easy access to all the tube headers therein forinspection, repairing and plugging of tubes or for removal andinstallation thereof.

Other and further objects of the invention will become apparent duringthe course of the following description.

We have discovered that the foregoing objects can be attained byproviding a particular configuration of manhole-cover supporting linkshingedly mounting the manhole to the shell of the steam generator.

Referring now to the drawings, in which like numerals represent likeparts in the several views:

FIGURE 1 represents a longitudinal section in elevation of a steamgenerator employing the present invention.

FIGURE 2 represents a longitudinal section in plan, taken along the line2 2 of FIGURE 1, of a steam generator employing the present invention,showing in phantom the manhole cover swung to one side of the manhole.

FIGURE 3 is similar to FIGURE 2, showing in solid lines the manholecover swung to the other side of the manhole opening, the position ofsaid manhole cover intermediate such open position and the closedposition be ing shown in phantom.

In the embodiment herein illustrated, the manhole cover and supportingmeans therefor constituting the present invention are seen as associatedwith a steam generator, the latter comprising drum or shell 1, withdished ends 2 and 3, containing six element header assemblies 4zz-4f anda gas collecting header assembly 15. Header assemblies 4a-4f and 5 each,in turn, are seen to comprise fourelement fittings 10 welded to stubs11, the latter in turn being welded to the header assemblies 4a-4f and5, U-tubes 12 welded to four-element fittings 10 and handhole plugs 13.

U-tubes 12 are spaced and supported in drum 1 by means of tube plates33, the latter resting on a grid of beams 34 and 35 which are tied tothe sides of the drum 1 and which are braced by box-like columns 36.Tube plates 53 are each associated with only one of the headerassemblies 4a-4f and 5 to permit the withdrawal from said drum 1 of anyone of said header assemblies 4a-4f and 5.

Access to the interior of drum 1 may be required for any of severalreasons. For instance, when a U-tube 12 develops a defect, the openingsin four-element fittings 10 corresponding to the defective U-tube may beplugged to permit continued operation of the steam generator until suchtime as it is convenient to replace the defective U-tube 12. When it isdesired to replace the defective U-tube 12, the header assembly 4a-4f or5 containing the defective U-tube 12 is removed from the interior ofdrum 1, the replacement operation is performed outside the drum 1, andthe repaired header assembly 4ax-4f or 5 is reinserted into the interiorof drum 1.

Manhole 55 permits access to the interior of drum 1. Manhole cover 56 islocated inside drum 1 and is provided with seat 57 which bears throughsuitable gasket means (not shown) against seat 58 of the manhole 55, theinternal pressure in the operating steam generator serving to force saidmanhole cover 55 and seat 57 tightly against seat 5S through theaforesaid gasket means.

Bracket 59, mounted to drum 1 above the center of manhole 55, rotatablysupports pin 60, the latter pivotally supporting link 61. Pin 62pivotally connects links 61 and 63. Pin 64 pivotally connects link 63and manhole cover 56 through brackets 65 secured to manhole cover 56`adjacent the center thereof. With this supporting arrangement, manholecover 56 can be moved to either side of manhole 55, as shown in FIGURES2 and 3, away from the side of drum 1 where space is required forworking on equipment such as header handholes, etc. This feature permitsa drum of shorter length to be used.

, vasm/nii It is apparent that all of the header assemblies 1a-4f and 5can be removed or installed one by one through the manhole 55. Welds 66which join these assemblies to other piping in drum 1 such as conduits15, 17, 20, and which join together the several parts of conduit 23, canbe cut and rewelded easily to facilitate such removal or installation ofthe header assemblies 411-43c and 5.

It will be seen that we have provided an easy-to-open manhole cover,which can be swung to either side of the manhole in the'drum head,providing quick access to the headers for inspection, repair andplugging of tubes, and for removal of header assemblies.

The construction and operation of the specic steam generator hereinbriey described insofar as considered necessary to a full understandingof the present invention forms, of course, no essential part of thepresent invention, and it is to be understood that the present inventionis capable of use with apparatus of other types. A complete descriptionof the construction and operation of the specific steam generator isfound in the previously mentioned copending application Ser. No. 51,043.v

We claim:

1. Manhole sealing means for use with a shell having a manhole openingand adapted to be swung to one side of said manhole opening orselectively to the other side thereof, comprising manhole cover means insaid shell engageable with the periphery of said manhole opening to sealoff said shell, a first vertically disposed pin mounted inside saidshell above and clear of the manhole opening, a rst link pivotallysupported on said rst pin clear of said manhole opening for swingingmovement in a horizontal plane, a second vertically disposed pin mountedto the inner face of said manhole cover means, a second link pivotallysupported on said second pin, said second link and said manhole covermeans being rotatable relative to each other in a horizontal plane, anda third vertically disposed pin joining said rst and second links forrelative swinging movement in a horizontal plane.

2. Manhole sealing means for use with a shell having a manhole openingand adapted to beswung to one side of said manhole opening orselectively to the other side thereof, comprising: Y

'i'.(a) manhole cover means engageable with the periphery of saidmanhole opening to sealoff said shell,

(b) a first pin mounted to said shell clear of said manhole opening withits longitudinal axis oriented towards the center of said manholeopening and intermediate the two extreme positions of said manholecover,

(c) a rst link pivotally supported on said rst pin clear of said manholeopening for swinging'movement in a plane perpendicular to thelongitudinal axis of said first pin,

(d) a second pin mounted to said manhole cover means with itslongitudinal axis parallel to the longitudinal axis of said iirst pin, Y

(e) a second link pivotally supported on said second (f) said secondlink and said manhole cover means being rotatable relative to each otherin a plane perpendicular to the longitudinal axes of said iirst andsecond pins, and

(g) a third pin with its longitudinal axis parallel to the longitudinalaxes of said first and secondpins joining said rst and second links forrelative swinging movement in a plane perpendicular to the longitudinalaxes of said lirst, second and third pins.

References Cited UNITED STATES PATENTS 1,924,279 8/ 1933 Harter 220-252,657,823 11/1953 Skinner 220-34 THERON E. CONDON, Primary Examiner.

l AMES B. MARBERT, Examiner.

